The resistance of polymer-based conductive composite material remains extremely low at room temperature and is sensitive to temperature change. In other word, the resistance will instantly increase to thousand times to open-circuit conditions when the temperature reaches a critical temperature or the circuit has over current, so as to protect circuit.
With the development of intelligent mobile terminals, the development trend of electronic elements is miniaturization with high holding current. However, the performance of traditional circuit protection components mounted on the surface of the circuit board is so difficult to improve further due to the space limitation of battery pack. If the PTC over-current protection device is embedded into the copper clad laminate, which can not only greatly reduce the limitation on circuit protection element thickness, but also provide more design space to the PTC element. Moreover, the PTC elements are sealed in the copper clad laminate, which greatly reduces negative impact on PTC elements from the external environment, so the circuit protection assembly has an excellent environmental reliability.